(a) Field of the Invention
This invention relates to a pump assembly for an atomizing piston pump and more particularly concerns a pump assembly for an atomizing piston pump of the kind comprising a first piston slidably located in a first cylinder to define a first variable volume space, a second piston slidably located in a second cylinder to define a second variable volume space in communication with the first space, a fluid flow passage through the first piston, first valve means for opening and closing the passage, first biasing means urging the first valve means into a position closing the passage, and second biasing means urging the second piston towards a position corresponding to the minimum volume of the second space.
(B) Prior Art
This type of pump assembly is known, for example, from British Pat. No. 1136848. Known pumps however, have the disadvantage that the first valve means when opened has no means to maintain it open and this can lead to an uneven flow of the contents out of the pump, as the valve opens and closes due to fluctuating pressure in the cylinders. Incomplete atomization and the formation of droplets, particularly when the piston handle is released, are another possible disadvantage.
It is also known, for example from British Pat. No. 1051552, to have a liquid dispensing pump with a single cylinder and piston in which the flow-controlling valve is opened immediately the operating handle is depressed. This type of pump also has the disadvantage that the flow of contents from the pump tends to be uneven, since the valve is open at all times when the operating handle is depressed and the flow of contents is therefore largely controlled by the pressure applied to the handle by the operator.
It is therefore an object of the present invention to provide a pump assembly which avoids or reduces these disadvantages and provides a flow of contents from the pump at constant or very nearly constant pressure.